The difficulties in sectioning frozen biological objects for electron microscopic investigations are overcome by Steere's freezing-etching method. In order to test this method and to open up a wide field of application, the new freezing-ultramicrotome has been designed. The apparatus consists of the combination of an ultramicrotome with freezing-drying and shadow-casting installations in the same vacuum container. The preliminary results show, on the one hand, the practicability of all preparational steps and, on the other, that it is possible to resolve internal structures of cell organelles and even macromolecular patterns.